This invention relates to the feeding of molten strands of plastic to a discharge trough, and, more particularly, to a discharge trough which is positionable either under or away from the fall line of the strands as they emerge from nozzles. When the trough is moved away from the strands, they fall freely beside it and are not collected in the trough.
A representative drainage trough for molten plastic strands is disclosed in German Pat. No. 2,503,455. The drainage trough of this patent has, at its upper end, a flap that is mounted on a perpendicular axle and can be pivoted to occupy one of two positions: An operating position and a non-operating position. In the operating position the flap is pivoted into contact with the trough to catch the emerging strands from the nozzles and feed them into the trough where coolant is applied. In the non-operating position, the flap is pivoted away from the trough so that the strands emerging from the nozzles fall between the flap and the trough.
When the flap is in its non-operating position, the material which initially emerges from the nozzles is kept from the trough since it generally contains contaminants or has not yet attained a final uniform composition. Under these circumstances, if the flap is moved to its operating position, it traverses the fall line of the strands which contact and become suspended from the flap. In order to prevent this occurrence, the flow of molten material can be terminated during the time interval when the flap is being moved from its non-operating to its operating position. Alternatively, the flow of molten material can be interrupted by having the operator use a stopping element at the nozzles. These procedures are disadvantageous and time consuming.
Accordingly, it is an object of the invention to facilitate the feed of molten strands of plastic to a collection trough.
A related object is to avoid the feed of contaminated and non-uniform plastic material to a collection trough. Another related object is to achieve the feed of relatively uniform strands of plastic material to a collection trough and avoid periodic stoppages for extensive cleaning and removal of contaminated and non-uniform materials from the collection trough.
Another object of the invention is to avoid the disadvantages associated with the use of a pivoted flap in connection with the operation of a collection trough and the associated spillage and soilage associated with the operation of such a flap.